I recently upgraded from 32 bit to 64 bit Arch Linux as I want to get into some 64 bit nitty-gritties. And I did it within a running system, that is, without re-installing the OS. While it sounds adventurous, Arch Linux’s migration guide made it without any surprises. The most tedious task was to remove everything installed through yaourt. Additionally, the multilib repository worked wonders for installing 32 bit applications like Skype and Wine. Even the flash plugin is working flawlessly. I have not seen a visible difference in performance for normal desktop applications but I will do some tests for server and multimedia applications and report them here.